Testing a detection dog to locate bumblebee colonies and estimate nest density

Bumblebee nests are difficult to find, hampering ecological studies. Effective population size of bumblebees is determined by nest density, so the ability to quantify nest density would greatly aid conservation work. We describe the training and testing of a dog to find bumblebee nests. The dog was trained by the British army, using B. terrestris nest material. Its efficacy in finding buried nest material of a range of bumblebee species was 100%, and no false positives were recorded, suggesting that the dog was able to generalize across Bombus species. The dog was then used to locate bumblebee nests in four different habitats on the island of Tiree, west Scotland. The dog located 33 nests, and nest densities recorded varied from 0 to 1.86 nests per hectare, according to species and habitat. Habitat preferences appeared to be evident among the bumblebee species, with most B. muscorum nests in machair and all of the B. distinguendus nests being in dunes. We conclude that the technique has great potential, but note that using a dog to detect nests in more densely vegetated habitats may be less successful.